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FHWA Home / Safety / Local and Rural Road / Delta Region Transportation Development Program

Delta Region Transportation Development Program: Rural Safety Innovation Program Evaluation – Final Report

Chapter 1. Introduction

Background

The Rural Safety Innovation Program (RSIP) is one of several key programs under the United States Department of Transportation's (USDOT) Rural Safety Initiative. The goal of the initiative is to improve safety on rural roads, resulting in a decrease in the loss of lives and injuries. As part of the RSIP, nine highway agencies in the Delta Region of the United States received funds to implement highway safety improvements towards the achievement of this overall goal. The objective of this research project was to evaluate the effectiveness of the RSIP projects implemented by the nine highway agencies toward achieving this goal of reducing fatalities and injuries on rural roads. By quantitatively estimating the safety effectiveness of specific countermeasures (or combinations of countermeasures) and by presenting "lessons learned" by agencies through their experiences of implementing specific countermeasures, the knowledge gained from the evaluations can benefit other highway agencies when making funding decisions concerning future safety improvement projects and programs.

The RSIP includes several elements. This evaluation of the RSIP focuses on the Delta Region Transportation Development Program (DRTDP). Nine agencies implemented a range of safety improvement projects as part of the RSIP-DRTDP. Table 1 lists the agencies that received safety funding through the DRTDP and the types of countermeasures implemented with those funds. In general, it can be assumed that the respective agencies identified high-risk locations (e.g., roadway segments, curves, or intersections) for safety improvement based on crash data and local knowledge and selected countermeasures for implementation based on the anticipated effectiveness of the countermeasures and their applicability to a systematic approach to implementation. The types of safety programs implemented by the agencies differ with respect to the types of countermeasures implemented and the related collision types targeted for remediation.

Table 1. Agencies and Countermeasures Involved in the RSIP-DRTDP

RSIP Project No./Agency Countermeasure/Improvement Types General Site Attributes
RSIP Project 25: Tennessee Department of Transportation (TDOT) Signing inventory/assessment system Rural state highways
RSIP Project 27: Mississippi Department of Transportation (MDOT) Centerline rumble strips and clear zone restoration Rural two-lane roads
RSIP Project 28: Hinds County, MS Signing, striping, and rumble strips Rural two-lane roads
RSIP Project 31: Grant Parish, LA Striping, rumble strips, raised pavement markers, flashing beacon warning signs, large arrow signs, chevrons, and other warning signs Rural two-lane roads
RSIP Project 32: Missouri Department of Transportation (MoDOT) Dynamic message signs on Interstate highways Rural interstates
RSIP Project 33: Arkansas State Highway and Transportation Department (AHTD) Cable median barrier on an Interstate highway Rural interstates
RSIP Project 34: Rapides Parish, LA Striping, rumble strips, raised pavement markers, flashing beacon warning signs, large arrow signs, chevrons, and other warning signs Rural two-lane roads
RSIP Project 36: Illinois Department of Transportation (IDOT) Advance curve warning signs, speed plates, chevrons, and raised pavement markings Horizontal curves on rural two-lane roads
RSIP Project 37: Louisiana Department of Transportation and Development (La DOTD) Signing and marking improvements at intersections Intersections on rural roads

Objective and Scope

The objective of this research project was to evaluate the effectiveness of the highway safety improvement projects implemented under the RSIP-DRTDP toward reducing fatalities and injuries on rural roads. Due to the availability of data and the nature of the projects, several levels of safety evaluations were performed. Three projects were selected for detailed quantitative evaluation. One project lent itself to a simpler quantitative analysis rather than a rigorous statistical analysis because it lacked a sufficient number of treatment sites (and mileage), and two projects were more suited to a qualitative, rather than quantitative, analysis, focusing on lessons learned by the agencies during implementation of their program. Finally, three projects were not included in the evaluation due to insufficient data and/or the ability to link all of the necessary crash, traffic volume, and roadway inventory data for analysis purposes. Table 2 shows the level of analysis performed for each RSIP project, as part of this research, and the projects selected for the analyses.

Table 2. Levels of Evaluation and Agencies Involved

RSIP Project No./Agency Level of Evaluation
RSIP Project 25: Tennessee Department of Transportation (TDOT) Qualitative evaluation
RSIP Project 27: Mississippi Department of Transportation (MDOT) Detailed quantitative evaluation
RSIP Project 28: Hinds County, MS Not evaluated
RSIP Project 31: Grant Parish, LA Not evaluated
RSIP Project 32: Missouri Department of Transportation (MoDOT) Qualitative evaluation
RSIP Project 33: Arkansas State Highway and Transportation Department (AHTD) Simpler quantitative evaluation
RSIP Project 34: Rapides Parish, LA Not evaluated
RSIP Project 36: Illinois Department of Transportation (IDOT) Detailed quantitative evaluation
RSIP Project 37: Louisiana Department of Transportation and Development (La DOTD) Detailed quantitative evaluation

Research Approach

At the beginning of the project, the research team contacted the nine highway agencies involved in the RSIP-DRTDP to discuss implementation and evaluation of their projects. The first task was for the research team to gain a detailed understanding of each RSIP project. Through a series of teleconferences, the research team gathered detailed information on each of the projects, identified the specific evaluation opportunities for each project, discussed the availability of data for use in the analyses, and identified key contacts within the highway agencies for data requests.

Following the teleconferences, the research team developed an evaluation plan for each project. Where practical, the research team conducted an observational before/after evaluation of the differences in crash frequency and severity for specific countermeasures or combinations of countermeasures using the Empirical Bayes (EB) method. Two advantages of the EB method over other analysis approaches are that the EB method can compensate for regression-to-the- mean bias and that existing safety performance functions (SPFs) can be used in the analyses rather than developing new SPFs for each evaluation. Existing SPFs from the Highway Safety Manual (HSM; AASHTO, 2010) and Safety Analyst were calibrated and used as appropriate in this type of analysis. Crash, traffic volume, roadway inventory, and countermeasure data were obtained for the analyses from discussions with project personnel, electronic databases, review of aerial mapping tools, and field visits. For projects that did not lend themselves to a detailed quantitative before/after evaluation using the EB method, either a simpler comparison of crashes before and after installation of the countermeasures was performed, or a qualitative evaluation was performed by gathering data from available reports and interviews with project personnel.

Outline of Report

The remainder of this report is organized as follows:

 

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